title: Effects of small intestinal glucose load on blood pressure, splanchnic blood flow, glycemia, and GLP-1 release in healthy older subjects.
abstract: Postprandial hypotension is an important problem, particularly in the elderly. The fall in blood pressure is dependent on small intestinal glucose delivery and, possibly, changes in splanchnic blood flow, the release of glucagon-like peptide-1 (GLP-1), and sympathetic nerve activity. We aimed to determine in healthy older subjects, the effects of variations in small intestinal glucose load on blood pressure, superior mesenteric artery flow, GLP-1, and noradrenaline. Twelve subjects (6 male, 6 female; ages 65-76 yr) were studied on four separate occasions, in double-blind, randomized order. On each day, subjects were intubated via an anesthetized nostril, with a nasoduodenal catheter, and received an intraduodenal infusion of either saline (0.9%) or glucose at a rate of 1, 2, or 3 kcal/min (G1, G2, G3, respectively), for 60 min (t = 0-60 min). Between t = 0 and 60 min, there were falls in systolic and diastolic blood pressure following G2 and G3 (P = 0.003 and P < 0.001, respectively), but no change during saline or G1. Superior mesenteric artery flow increased slightly during G1 (P = 0.01) and substantially during G2 (P < 0.001) and G3 (P < 0.001), but not during saline. The GLP-1 response to G3 was much greater (P < 0.001) than to G2 and G1. Noradrenaline increased (P < 0.05) only during G3. In conclusion, in healthy older subjects the duodenal glucose load needs to be > 1 kcal/min to elicit a significant fall in blood pressure, while the response may be maximal when the rate is 2 kcal/min. These observations have implications for the therapeutic strategies to manage postprandial hypotension by modulating gastric emptying.
authors.affiliation: University of Adelaide, Discipline of Medicine, Royal Adelaide Hospital and National Health and Medical Research Council Centre of Clinical Research Excellence in Nutritional Physiology, Interventions and Outcomes, South Australia, Australia.
authors.forename: Lora
authors.initials: L
authors.lastname: Vanis
authors.forename: Diana
authors.initials: D
authors.lastname: Gentilcore
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Rayner
authors.forename: Judith M
authors.initials: JM
authors.lastname: Wishart
authors.forename: Michael
authors.initials: M
authors.lastname: Horowitz
authors.forename: Christine
authors.initials: C
authors.lastname: Feinle-Bisset
authors.forename: Karen L
authors.initials: KL
authors.lastname: Jones
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology*; D001786:Blood Glucose / Q000378:metabolism*; D001794:Blood Pressure / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D005746:Gastric Emptying / Q000187:drug effects / Q000502:physiology; D052216:Glucagon-Like Peptide 1 / Q000097:blood*; D005947:Glucose / Q000378:metabolism / Q000494:pharmacology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007022:Hypotension / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology; D007328:Insulin / Q000097:blood; D007421:Intestine, Small / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D009638:Norepinephrine / Q000097:blood; D019518:Postprandial Period; D013152:Splanchnic Circulation / Q000187:drug effects* / Q000502:physiology; D013564:Sympathetic Nervous System / Q000502:physiology
chemical_list: D001786:Blood Glucose; D007328:Insulin; D052216:Glucagon-Like Peptide 1; D005947:Glucose; D009638:Norepinephrine